China stocks rallied, with the up 0.8 percent and the Shanghai Composite up 2.3 percent overnight. After years of discussion, the Hong Kong Stock Exchange and Shanghai will finally open a formal stock trading link on Nov. 17.

Many mainland China firms already dual list in Hong Kong, mainly large state-owned enterprises, but this trading link will open up many more smaller companies.

Hong Kong investors will be able to buy and sell an additional 568 Shanghai-listed equities. Mainland investors will be able to buy and sell 268 Hong Kong-listed stocks. This opens up many domestic Chinese stocks for the first time.

Some fund managers were already allowed to invest in Chinese stocks through a quota system that was capped at $105 billion. But the new system will allow most investors to buy shares on the Shanghai Stock Exchange, opening up the $2 trillion market fully to foreign investment, though there will be some quotas on inflows into China that will still be applied.